The present invention relates to a new and improved construction of an actuation apparatus for the movable mold parts or halves of a molding machine, in particular an injection molding machine, especially for the manufacture of foamed articles or the like, which apparatus is of the type comprising pairs of togglelever rods movable in essentially parallel planes spaced from one another, the toggle-lever rods being located between a movable mold support plate or platen and a stationary toggle plate, there further being provided a driven toggle head means for extending or retracting the toggle-lever rods.
Actuation devices of this general type have been disclosed, for instance, in Swiss Pat. No. 331,325 and U.S. Pat. No. 3,577,596. In order to increase the stroke of actuation devices of this type it is considered obvious to those versed in the art to construct the linkages and levers of the toggle-lever rods as long as possible. The positional offsetting of parallelly arranged toggle-lever rods insures that the latter are able to overlappingly extend and collapse or bend past one another. Due to the offsetting positional arrangement of the toggle-lever rods and therefore the points of application of the forces at the movable mold support plate and the stationary toggle plate there prevails, however, an unfavorable distribution of the forces which can result in undesired moments in the planes of the movable mold support plate and the toggle plate, respectively, if there are not undertaken measures for suppressing the development of such moments.